Standardized compositions which facilitate swallowing in dysphagic subjects

ABSTRACT

Disclosed are kits containing two or more viscosity-standardized, edible solutions for evaluating human subjects for dysphagia. Also disclosed are corresponding methods of using the kits for diagnosing dysphagia and for radiographic imaging of the oropharynx.

[0001] This is a continuation-in-part of co-pending application Ser. No.09/442,704, filed Nov. 18, 1999, which claims priority to provisionalapplication Serial No. 60/151,213, filed Aug. 27, 1999, the contents ofboth of which are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The invention is directed to standardized, viscosity-modified,edible formulations for use with dysphagic patients and methods to gaugethe viscosity of modified foods using the standardized formulations. Theformulations described herein can also be combined with a radio-opaqueagent to facilitate improved dynamic fluoroscopic imaging of theoropharynx, hypopharynx, etc.

BACKGROUND OF THE INVENTION

[0003] The oropharyngeal physiology involved in a normal swallow is anexceedingly complex series of coordinated actions. A host of verydifferent medical conditions, both physical and neurological in nature,can alter normal swallowing. For example, patients suffering stroke,Alzheimer's disease, amyotrophic lateral sclerosis, or traumatic braininjury can exhibit abnormal swallowing. In many instances, the abnormalswallow can and does cause aspiration of food material, both liquids andsolids, into the lungs. This is especially prevalent (andlife-threatening) in bed-ridden patients. Aspiration of foreign materialinto the airways leads to increased morbidity in hospitalized patientsand can lead to pneumonia. Abnormalities in the human swallow, whetheror not the condition results in aspiration of foods, is calleddysphagia.

[0004] A normal human swallow can be separated into four semi-distinctphases: 1) oral preparation; 2) the oral phase; 3) the pharyngeal phase;and 4) the esophageal phase. Patients who have suffered a stroke,traumatic brain injury, or neuromuscular disorder (such as MS or ALS)have an increased risk of aspiration, and may have difficulty with theoral phase, the pharyngeal phase, or both. For instance, weak and/oruncoordinated muscle movement when chewing, or in the initial oral phaseof swallowing, can cause food to fall into the pharynx and into the openairway. This often occurs before the completion of the oral phase ofswallowing. Or impaired propulsion can result in residue in the oralcavity, valleculae, or pharynx after the swallow, when the residue maybe inhaled into the trachea. Or a delay in the onset of the pharyngealswallowing response can result in food falling into the airway duringthe delay when the airway is open. Or reduced peristalsis in the pharynxcan leave residue in the pharynx after the swallow is completed that canfall or be inhaled into the airway. Additionally, laryngeal orcricopharyngeal dysfunction can also lead to aspiration because ofdecreased closure of the airway during swallowing. Any of theseconditions, or a combination of these conditions, can lead to aspirationof food into the airways.

[0005] To detect and evaluate patients who have dysphagia or are at riskof developing dysphagia, speech pathologists currently employ a roughlystandard procedure for initially evaluating a patient's swallow. Abedside swallow exam performed by most speech pathologists firstevaluates the patient's medical history, respiratory status, level ofresponsiveness, and level of cognitive impairment, if any. Evaluatingswallowing can be especially difficult in patients with moderate toadvanced cognitive impairment due to the inability of the patient tounderstand and to follow instructions.

[0006] A physical examination of the oropharynx is then performed. Themuscles involved in mastication, the lips, the tongue, and the palateare examined. The position of the patient when tested (prone, seated,standing) is noted as this can have a profound effect on the swallowingmechanism. The patient's empty mouth (“dry”) is evaluated. The patientis then asked to swallow one or more thin liquids, thick liquids, pureedtextured, and/or solid textured foods to evaluate the swallow mechanism.In particular, the speech pathologist looks for a host of telltale signsof dysphagia such as gurgling, impaired vocal quality post-swallow,coughing, nasal regurgitation, and multiple swallows, as well as anyvisible signs that may indicate risk for aspiration.

[0007] While the standard bedside swallow exam to screen patients isbeneficial for evaluating patients at risk for dysphagia, it sheds verylittle light on the whether the patient is actually aspirating and evenless light on where in the swallow cycle the defect arises. Manypatients, due to concomitant neurological defects, will silentlyaspirate, giving no indication during the bedside exam as to theircondition. Aspiration in dysphagic patients, however, can be detectedusing a modified barium swallow fluoroscopic examination. Videofluoroscopy of the swallow mechanism is performed regularly to elucidatemore clearly the anatomical or neurological deficit causing thedysphagia.

[0008] Dynamic fluoroscopic evaluation of the swallow, however, is notwithout its attendant difficulties and shortcomings. For instance, theimaging compositions conventionally used for fluoroscopic exams arethick suspensions of barium sulfate. Barium is employed because of itslarge X-ray absorption cross-section, which makes it radio-opaque. Theuse of barium sulfate suspensions as a radiological contrast medium hasa number of drawbacks. A first drawback is that conventional bariumsulfate suspensions generally have either poor adhesion to the walls ofthe oropharynx or too much adhesion. These compositions, having beeninitially designed to image the gastrointestinal tract, have not beenaltered much, if any, for use in imaging the mouth and throat. If thewalls of the oropharyngeal tract are not sufficiently coated with thecontrast agent, an X-ray image cannot be generated; there simply is notenough contrast to visualize the relevant structures. Conversely, if thesuspension is made thicker to encourage adhesion, the thick, chalkysuspension actually coats the mouth and throat and physically alters themovement of the muscles used for swallowing. Consequently, the imagegenerated is not necessarily indicative of the true swallow responseexhibited by the patient. Further, total clearance of material from theoropharyngeal and esophageal cavities would be a useful visual cue todetermine whether the function of these structures is within normallimits. If the oropharynx is coated with too much contrast agent, thedense X-ray cross-section creates a complete opacity in the resultantX-ray exposure, which does not provide sufficient detail of thestructures involved in swallowing. A complicating factor is the tasteand chalky texture of barium suspensions, which makes them generallyunpleasant to hold in the mouth and to swallow. Substances that are morefood-like in taste and texture would more likely elicit a morerepresentative swallow response.

[0009] See, for example, U.S. Pat. No. 4,020,152 to Heitz, whichdescribes barium titanate and barium zirconate X-ray contrast agents.This patent specifically notes that it is quite difficult to generatefluoroscopic images of the oropharyngeal cavity. Heitz states thatpatients have great difficulty in holding a mouthful of contrast mediumat the very back of their throats for a long time without swallowing.When the patient swallows the barium sulfate suspension, it slides overthe mucous membranes, often without leaving sufficient contrast agent inplace to generate an image. Heitz believes the lack of adhesion is dueto the saliva covering the walls of the oropharynx, which substantiallyreduces the adherence of a barium sulfate suspension. As a result,radiological examination of this key physiological intersection, thejunction where aspiration occurs, is difficult and often leads to onlymediocre imaging. Failure to generate a clean radiological image of theswallow leads to imprecise diagnosis and treatment.

[0010] Moreover, once a patient has been diagnosed as having dysphagiaand is known to be aspirating foods, some compensatory treatment must beimplemented to prevent further aspiration. One method widely employed isto alter the consistency (i.e., the viscosity) of liquid foods.Thickened liquid foods are thought to inhibit aspiration by providinggreater mechanical resistance to the muscles involved in swallowing andproviding greater “mouthfeel” to the patient. See, for example, U.S.Pat. No. 5,932,235, to Ninomiya et al.: This patent describes a jelliedpreparation containing carrageenan, locust bean gum, and a polyacrylicacid. The preparation can be used to thicken liquid foodstuffs.

[0011] In hospital, nursing home, and clinical settings, thickenedliquids deemed to be “nectar thick” or the more viscous “honey thick”are used to feed dysphagic patients. For instance, preferred liquidfoods such as milk, coffee, or tea are thickened with an addedthickening agent prior to being fed to a dysphagic subject. However,there has not been implemented any objective set of criteria to definethe levels of thickness/viscosity which constitute a nectar thickcomposition versus a honey thick composition. The health provider simplythickens the desired food to a subjective thickness and provides it tothe patient. This lack of standardization fosters great variability inpractice. In short, individual speech pathologists, dieticians, foodservice managers, and food manufacturers arbitrarily determine, basedupon their own subjective evaluation, what constitutes a nectar thickcomposition and a honey thick composition. In the vast majority ofinstances, no objective measurement of the increased viscosity of themodified food is taken. If a measurement is taken, it is done usingrough, empirical evaluations of viscosity, such as the Line SpreadingTest (LST), a test developed in the 1940s to gauge the consistency offoods. See Grawemeyer, E. A. and Pfund, M. C. (1943) “Line spread as anobjective test of consistency,” Food Research 8:105-108. This greatlyhinders gathering detailed information on the efficacy of usingthickened liquids in the treatment of dysphagia.

[0012] Therefore, there continues to be a long-felt and unmet need inthe study of dysphagia for a viscosity-standardized set of ediblecompositions for both the gross evaluation of dysphagia and for acorresponding viscosity-standardized set of edible compositionscontaining a radio-opaque agent for use in the radiographic imaging ofthe mouth and throat.

SUMMARY OF THE INVENTION

[0013] A first embodiment of the invention is directed to a kit ofindividual viscosity-standardized edible solutions for evaluating humansubjects for dysphagia. The kit comprises at least two solutions, thetwo solutions being selected from the following group: a first ediblesolution having a known viscosity of from about 1 cp to about 60 cp atabout 23° C., the first edible solution disposed in a first container; asecond edible solution having a known viscosity of from about 300 cp toabout 2000 cp at about 23° C., the second edible solution disposed in asecond container; and a third edible solution having a known viscosityequal to or greater than about 3000 cp at about 23° C., the third ediblesolution disposed in a third container.

[0014] In alternative formulations of the first embodiment, the kit maycontain a second edible solution having a viscosity of between about 300cp to about 500 cp or between about 500 cp to about 1500 cp. In thepreferred formulation, the third edible solution as described in theimmediately preceding paragraph has a viscosity of between about 3000 cpto about 5000 cp, and more preferably still between about 3000 cp toabout 4000 cp.

[0015] A second embodiment of the invention comprises the kit asdescribed in the two preceding paragraphs, wherein the first, second,and third edible solutions comprise an imaging agent. It is preferredthat the imaging agent comprises a radio-opaque imaging agent,preferably a barium-containing compound, and more preferably still abarium sulfate-containing compound.

[0016] The kit may also comprise, instead of solutions, compositions ofmatter that are capable of being diluted to yield viscosity-standardizededible solutions as described hereinabove. Thus, such a kit comprises atleast two compositions of matter selected from the group consisting of afirst composition capable of yielding upon dilution a first ediblesolution having a known viscosity of from about 1 cp to about 60 cp atabout 23° C.; a second composition capable of yielding upon dilution asecond edible solution having a known viscosity of from about 300 cp toabout 2000 cp at about 23° C.; and a third composition capable ofyielding upon dilution a third edible solution having a known viscosityequal to or greater than about 3000 cp at about 23° C.

[0017] A third embodiment of the invention is directed to acorresponding method for using the above-described kits to evaluate ahuman subject for dysphagia. The method comprises the steps of providingat least two of the first, second, and third edible solutions asdescribed hereinabove. Then swallowing in the subject is evaluated forindications of dysphagia during and after the subject swallows one ofthe edible solutions and then during and after the subject swallowsanother of the edible solutions (i.e., one of the solutions having adifferent viscosity from the first solution swallowed). Because the twosolutions have different, but known and standardized viscosities, bycomparing the swallowing dynamics exhibited by the subject duringingestion of the two solutions, a more accurate diagnosis of the subjectcan be made. Additionally, because the solutions have a standardviscosity, the swallowing dynamics of two different subjects or betweendifferent populations of subjects can be compared accurately.

[0018] In the preferred formulation of the method, the edible solutionscomprise a radio-opaque imaging agent that does not leave an artificialcoating in the mouth and oropharynx after swallowing is complete.Swallowing by the subject is preferably evaluated by radiography.

[0019] In both the kit and the corresponding method, it is preferredthat the edible solutions comprise a tasty and familiar base liquidvehicle, such as a non-pulpy fruit juice, or a liquid that has beentreated to have an identifiable food flavor. The vehicle is adjusted tothe required viscosity by adding a thickening agent thereto. Apple juiceis the preferred vehicle. Because the solutions use a vehicle having afamiliar taste, far more useful information is generated regarding theswallowing defects exhibited by the patient because the patient tends toswallow more naturally. This is not the case when a patient is offered acontrast solution that has an offensive taste, odor, or consistency.

[0020] The utilities of the subject compositions and methods areseveral-fold. A primary utility is that by using standardized solutions,consistency in treating dysphagia is promoted. Rather than supplyingpatients an arbitrarily thickened food or X-ray imaging product, thepatient is supplied a solution of known viscosity. The patient's abilityto swallow the solution properly (e.g., without aspiration, retention,regurgitation, and the like) is then evaluated, either by a grossphysical exam or radiographic means or other visualization means,including X-ray, magnetic resonance imaging, and the like. Using two ormore viscosity-standardized solutions allows the results of two (ormore) distinct swallowing studies (e.g., one using the first solution,the other using the second solution) to be compared and contrasted.Moreover, it allows the results from different patients to be compareddirectly, without variations in the viscosity of the edible solutionsintroducing uncontrolled variables into the comparison.

[0021] The solutions described herein are useful in radiographic imagingof the mouth because they taste more food-like than conventionalbarium-containing imaging agents and are therefore more palatable. Thespecific viscosities recited herein for the solutions also promote theproper amount of adhesion between the solutions and the mucus membraneslining the mouth and throat. Consequently, the solutions tend to deposita sufficient amount of imaging material on the mucus membranes togenerate a radiographic image, but do not deposit so much imagingmaterial as to change the swallowing dynamics of the patient understudy, nor to leave an artificial coating after swallowing is complete.This is a distinct improvement over conventional barium agents, whosethick, chalky consistency is neither palatable, nor conducive to thegeneration of good radiographic images of the throat and mouth.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a graph depicting the line spread distance versus theapparent viscosity for a population of pre-thickened edible solutions.The sample volume used to generate each data point was 50 mL.

[0023]FIG. 2 is a graph depicting the line spread distance versus theapparent viscosity for a population of pre-thickened edible solutions.The sample volume used to generate each data point was 100 mL.

DETAILED DESCRIPTION

[0024] When speech pathologists thicken liquids, one of the propertiesthey are changing is viscosity. Liquids may be described by severalproperties, including viscosity, density, and elastic parameters, amongothers. As described herein, standardized solutions for evaluatingdysphagia are characterized using viscosity, as measured with aviscometer, as a key parameter. In simple terms, the torque required torotate a spindle immersed in the solution is measured. As discussed indetail by Li et al (1992) Dysphagia 7:17-30, viscous liquids areclassified as either Newtonian or non-Newtonian. A Newtonian liquidflows at a rate which is directly proportional to the applied shearforce while a liquid not obeying this proportionality is deemed to benon-Newtonian.

[0025] The complexity and cost of viscometers makes them impractical fordietitians and speech pathologists to utilize in most clinical settings.Therefore, clinicians often resort to simpler means of generating arough estimate of viscosity, such as the line spread test (LST) as apractical alternative to characterizing the viscosity of thickenedliquids.

[0026] The LST was originally developed in the 1940's as a simple toolto measure food “consistency.” See 8. Grawemeyer & Pfund (1943)FoodResearch 8:105-108, and Adams & Birdsall (1946) Food Industries 78-80.The LST measures the “flow” of a food/liquid by placing a standardamount of food/liquid in a cylinder, lifting the cylinder and allowingthe food/liquid to flow on a horizontal surface for 1 minute and thenmeasuring the distance it has spread. The simplicity of this tool isextremely appealing in clinical practice to measure objectively thegeneral consistency of thickened liquids. As described in the Examples,the LST can roughly distinguish between the viscosity of pre-thickenedliquids, and may be a first step toward establishing the utility of thistool in clinical practice.

[0027] However, the LST is not overly discriminating as a tool tomeasure viscosity. Thus, the principal object of the invention is toprovide a set or kit of solutions of known and standardized viscosity.The solutions in the kit come pre-made, as ready-to-use liquids, or inpre-measured dry powders or gels that can then be diluted with anappropriate liquid vehicle to yield solutions of the required viscosity.

[0028] The first embodiment of the invention is a pair ofviscosity-standardized solutions for evaluating dysphagia in humansubjects. Specifically, at least two edible solutions are required, thetwo solutions being selected from among: a first solution having aviscosity of between about 1 and 60 cp, a second solution having aviscosity of between about 300 and 2000 cp, and a third solution havinga viscosity great than about 3,000 cp.

[0029] Viscosity of the compositions is measured at room temperature,generally about 23° C., and can be determined using any number ofconventional and commercially available spindle-type viscometers, suchas those manufactured by Brookfield Engineering Laboratories,Middleboro, Mass. Brookfield's instruments use a rotating spindleimmersed in the fluid to measure viscosity. Brookfield's instruments areof the cone-and-plate rheometer-type design and are ideal for measuringthe viscosity of non-Newtonian fluids at low shear rates. The preferredinstrument from among Brookfield's offerings is Model LVDV1+, an18-speed model with digital readout. Viscometers and their operation arewidely known and will not be described in great detail herein. Fordetailed information regarding Brookfield's Model LVDV1+ viscometer, seeBrookfield's Manual No. M/92-021-M0101, available from the manufacturerand also on-line at www.brookfieldengineering.com. For detailedinformation regarding measuring viscosity, see Li et al, supra, andBrookfield's technical manual entitled “More Solutions to StickyProblems” (also available at www.brookfieldengineering.com).

[0030] For radiographic imaging of the mouth and throat, it is preferredthat compositions having the above-noted viscosities are formulatedusing a liquid base vehicle having an identifiable food flavor, such asa juice flavor or honey, chocolate, vanilla, etc. Apple juice isparticularly preferred a base vehicle. Apple juice is very advantageousfor this purpose because it is widely available, relatively inexpensive,and pulp-free. It is quite palatable and familiar to virtually everyone,and can be stored and transported as a concentrate. The liquid base canbe naturally or artificially flavored, and can also contain additionalcomponents such as colorants, preservatives, and the like. To the liquidvehicle is added a thickening agent and/or a radio-opaque imaging agent.Because a suspension of radio-opaque material will, by itself, increasethe viscosity of a thin liquid to within the above-noted viscosities,depending upon the nature of the suspension used, a thickening agent maynot be required to arrive at solutions having the desired viscosity.

[0031] Any other type of non-pulpy juice, liquid, or water may be usedas the vehicle. A fruit juice is much preferred as the vehicle, however,because of its familiar taste and aroma. An ultimate goal of theinvention being an accurate evaluation of the patient's true swallowingdynamics, presenting an imaging composition which is as closelysimulative as possible to a food the patient would normally ingest andenjoy is highly desirable.

[0032] The preferred thickening agent for use in the present inventionis a commercially available preparation marketed by Novartis (Basel,Switzerland) under the registered trademark “THICKENUP.” While the“THICKENUP” formulation is preferred, any suitable food thickener (e.g.,“THICK IT”-brand thickener (Milanti Co.) starch, sugars, glycols, etc.,may be used).

[0033] The preferred radio-opaque imaging agent is a suspension ofbarium sulfate. Suitable barium sulfate and barium sulfate suspensionsare available commercially from numerous sources. Preferred commerciallyavailable barium sulfate and edible suspensions thereof can be obtainedfrom the E-Z-EM Corporation, Westbury, N.Y. Specifically preferred arethe products bearing E-Z-EM catalog nos. L147, L164, L168, and L178(liquid barium sulfate suspensions), catalog no. 764 (high densitybarium sulfate suspension), and catalog no. 745 (bulk barium sulfate forsuspension). Particularly preferred for use in both the first and secondsolutions is “EnteroH” brand barium suspension (catalog no. L147), fromE-Z-EM.

[0034] It is critical when formulating the compositions to include theproper amount of imaging agent and/or thickener because both componentswill contribute to the ultimate viscosity of the composition and theremust also be the proper amount of imaging agent present in thecomposition to generate useful radiographic images (when an imagingagent is used). If there is too little imaging agent, the compositionwill be invisible to X-rays, if there is too much imaging agent, thecomposition will be too opaque.

[0035] For the first solution, the preferred formulation is as follows:

[0036] Commercially purchased apple juice at room temperature,(single-strength, about 6.5 to 7.0 brix, at about 23° C.), 140 mL, isadmixed with 90 mL of “Entero H” brand barium sulfate suspension,available commercially from E-Z-EM. The mixture is thoroughly agitateduntil uniform. To ensure consistency of application, it is muchpreferred that the composition be made no more than 2.5 hours beforeuse. The formulation should be administered at room temperature. Thisformulation yields a low-viscosity composition of about 25 cp.

[0037] For the second solution, the preferred formulation is as follows:

[0038] Commercially purchased apple juice at room temperature,(single-strength, about 6.5 to 7.0 brix, at about 23° C.), 30 mL, isadmixed with from about 170 to about 400 mL of “Liquid Polibar” brandbarium sulfate suspension, available commercially from E-Z-EMcorporation. The mixture is thoroughly agitated until uniform. To ensureconsistency of application, it is much preferred that the composition bemade no more than 2.5 hours before use. The formulation should beadministered at room temperature. This yields a solution having aviscosity of from about 300 to about 2000 cp.

[0039] For the third solution, the preferred formulation is as follows:

[0040] Commercially purchased apple juice at room temperature,(single-strength, about 6.5 to 7.0 brix, at about 23° C.), 120 mL, isadmixed with about 50 mL (3 tablespoons) of “THICKENUP” brand thickener.(As sold commercially, the “THICKENUP” thickener includes a slidingmeasuring spoon.) The juice and thickener mixture is agitated thoroughlyand allowed to sit undisturbed for no less than 10 minutes. To thismixture is added about 92 mL of “Liquid Polibar” brand barium sulfatesuspension, available commercially from E-Z-EM Corporation. The mixtureis again thoroughly agitated until uniform. To ensure consistency ofapplication, it is much preferred that the composition be made no morethan 2.5 hours before use. The formulation should be administered atroom temperature. This yields a solution having a viscosity of about3000 cp.

[0041] For radiographic imaging purposes, the patient is positionedlaterally before a suitable fluoroscopic device and asked to swallow oneor more of the three compositions. A video fluoroscope and suitablerecording equipment are then used to visualize and record the passage ofthe composition through the mouth and throat during and afterswallowing. If desired, the study can be performed using any combinationor both of the two edible solutions.

EXAMPLE

[0042] The following Example is included herein solely to provide a morecomplete and consistent understanding of the invention disclosed andclaimed herein. The Example does not limit the scope of the invention inany fashion.

[0043] Materials:

[0044] The Example explores whether pre-thickened liquids (from NovartisNutrition, Minneapolis, Minn.), whose viscosity has first been measuredwith a viscometer, can reliably be separated into “nectar” and “honey”categories using the Line Spread Test. According to Novartis'manufacturing standards, nine (9) of the samples tested were designatedas “nectar” and then (10) of the samples tested were designated as“honey” (19 samples total). The 19 samples were first examined using aBrookfield viscometer, and then evaluated using the Line Spread Test(LST).

[0045] Viscosity Measurements:

[0046] Each sample was tested using either a Brookfield HVT or LVTrotational viscometer (Brookfield Engineering, Stoughton, Mass.). Thesample to be measured was contained in either the small sample chamberprovided by Brookfield or a 600 ml Griffin low-form beaker, depending onthe spindle/chamber arrangement appropriate for each sample (for detailson equipment for viscosity measurement using these two Brookfieldinstruments, see “More Solutions to Sticky Problems,” available fromBrookfield Engineering). The shear rate and apparent viscosity of thenon-Newtonian liquids were estimated using the method described by Li etal. (1992) Dysphagia 7:17-30. (Note that while Newtonian liquidviscosity is a constant, regardless of liquid flow rate, non-Newtonianliquid viscosity is not. The “apparent viscosity” describes theinstantaneous viscosity at a given rate of flow). For uniformity betweendifferent fluids, the apparent viscosity for each fluid was computed ata shear rate of approximately 15 sect⁻¹. For the remainder of thisExample, the term “viscosity” refers to “apparent viscosity at a shearrate of 15 sec⁻¹,” unless otherwise noted.

[0047] Line Spread Test:

[0048] The standard LST, Mann & Wong (1996) J Am. Diet. Assoc.96:585-588, was carried out on a counter top using a piece of Plexiglaswith a template of pre-measured concentric circles spaced 0.25 inches(0.64 cm) apart placed beneath it. The counter top was confirmed to belevel with a carpenter s level. A PVC pipe, with an internal diameter of2 inches (5.08 cm) was positioned in the middle of the template andfilled with 50 ml of the sample to be tested. The tube was lifted andthe sample was allowed to spread for 1 minute. Measurements of thediameter of the spreading sample were taken at 90-degree increments andaveraged. to give the line spread reading. This test was carried outthree times to get an average line spread reading. For the Example, theLST was also carried out using a 100 ml sample size to explore howvolume might affect the line spread results.

[0049] Statistical Analyses:

[0050] For both LST and viscosity values, group means were computed fornectar and honey consistencies and differences between the twocategories tested using Student's t-test. To study the separationbetween nectar and honey consistencies further, a linear-discriminantanalysis was performed. This analysis generates a classification rule tocategorize each liquid into the nectar or honey group based on its LSTvalue. The rule is generated by maximizing the difference between thetwo groups in a least squares sense. Each value in the data set is thentested using the rule and the number of errors in classification wasdetermined. Statistical analyses were computed automatically using theSAS statistical program (The SAS Institute, Cary, N.C.).

[0051] Results:

[0052] Group values for the LST and viscosity are presented in Table 1(mean+SD). There was a highly significant difference in line spread testresults (both 50 and 100 ml) and viscosity values between nectar andhoney consistencies (p<0.0001 by Student's t-test). TABLE 1 CategoryViscosity @ 15 ^(s−1) LST (50 ml) LST (100 ml) Nectar 358.61 ± 77.9 12.67 ± 0.829 20.06 ± 1.45  Honey   1245.10 ± 357.4*     9.25 ± 0.50*  15.04 ± 0.73* 

[0053]FIGS. 1 and 2 show line spread distance plotted as a function ofviscosity for line spread volumes of 50 ml (FIG. 1) and 100 ml (FIG. 2).The first observation is that the LST discriminates very well betweendifferent classes of liquids. That is, the LST clearly differentiatesbetween the nectar versus honey consistencies in the present study. Asis clearly shown in both FIGS. 1 and 2, these pre-thickened nectar andhoney liquids fall into distinct categories, in terms of both linespread values and viscosity, in both the 50 ml and 100 ml test volumes.

[0054] The classification rules computed from the discriminant analysismay be expressed as the line spread value that separates nectar andhoney categories for each volume of sample tested. These separating linespread values are: 10.7 (50 ml sample, FIG. 1—horizontal dashed line)and 17.5 (100 ml sample, FIG. 2—horizontal dashed line). When thesamples were re-tested based on this rule, there were no errors inclassification, indicating that the line spread test does an excellentjob of discriminating between these two broad categories of liquids.

[0055] Beyond the gross separation into nectar versus honeyconsistencies, however, there is no apparent predictive value of theline spread test for estimating apparent viscosity. In other words, itdoes not appear to be possible to assign a one-to-one relationshipbetween apparent viscosity values and line spread test values.

[0056] Discussion:

[0057] The goal of this Example was to explore the utility of the LineSpread Test (LST) as an objective measure of thickened liquidconsistency. Because increased viscosity is often associated withthickened liquids, line spread and viscosity values were compared toexplore whether a relationship exists between the two tests. Two resultsemerge from this Example. On one hand, the LST was able to separatepre-thickened juices into nectar and honey categories unambiguously(i.e., with no errors), a separation also provided by viscositymeasurement. On the other hand, within this restricted group of liquids,there was no relationship between line spread and viscosity values. Inother words, there was no predictive value in terms of viscosity usingthe LST, apart from the overall separation into nectar and honeycategories. Thus, the LST is not an accurate substitute for aviscosity-standardized solution; a solution whose viscosity isaccurately known prior to being administered to the subject.

[0058] Based on these results, there are two possibilities concerningthe relationship between LST values and viscosity values. One is thatdecreased line spread test values are associated with increasedviscosity, but that the LST simply is not sensitive enough to detectdifferences in viscosity within a given category of liquids (i.e.,viscosity differences within the nectar or honey categories). If thiswere true, however, it would be expected that an increase in the volumeof test fluid from 50 to 100 ml would increase the sensitivity of theLST, and this was not found in the example (compare FIGS. 1 and 2).

[0059] A different possibility is that other fluid properties arealtered along with viscosity, and that it is one or more of these otherproperties that are reflected in the LST values. Indeed, one of thedifficulties in interpreting LST values is that several fluid propertiespossibly affect the final value. Density likely plays a role because thedriving force for liquid spreading is provided by gravity; viscosityplays a role through the retarding frictional forces at the liquid-solidinterface. Finally, elastic parameters, which relate to bolus“cohesiveness,” may also be important.

[0060] The role of elastic properties in the dynamics of the LST is alsosupported by a survey of the civil engineering literature. A commonlyused measure to field test the consistency of freshly mixed concrete iscalled the “slump” test. See, for example, Schowalter & Christianson(1998) J. Rheol. 42(4):865-870. This test is carried out in the samemanner as the LST, except that the height of the fluid pool afterspreading is measured rather than the radius to which the materialspreads. (Conservation of fluid volume may be used to relate the slumpheight to the line spread difference. The calculation is very simple andemphasizes the intimate link between these two tests.) Interestingly,this slump height has been shown to correlate with the “normalized yieldstress” of the concrete mixture. Yield stress is a measure of fluidelasticity and in these analyses is normalized by density, emphasizingthe multi-factorial nature of the physical process of spreading. Becauseconcrete has a much higher yield stress than typical liquid foodstuffs,the slump test results are not directly applicable to the ediblesolutions described herein. However, the correspondence between the twotests suggests that yield stress and density are fluid properties whichmay affect the line spread distance.

[0061] Clearly the mechanical behavior of liquid foodstuffs is complex;even more complex are their interactions with the swallowing system.However, the situation remains that: 1) dietary modifications are acommon treatment technique; and 2) there are no objective criteria forthickened liquid preparation for assessment and/or treatment. This hasled to little inter-clinician agreement and reliability in terms ofthickened liquid consistency. Therefore, there is a great need for apre-made solutions, or kits that yield solutions, of known andconsistent viscosity, thereby removing one source of uncertainty in thediagnosis and evaluation of dysphagia.

What is claimed is:
 1. A kit of individual viscosity-standardized ediblesolutions for evaluating human subjects for dysphagia, the kitcomprising at least two edible solutions selected from the groupconsisting of: (a) a first edible solution having a known viscosity offrom about 1 cp to about 60 cp at about 23° C., the first ediblesolution disposed in a first container; (b) a second edible solutionhaving a known viscosity of from about 300 cp to about 2000 cp at about23° C., the second edible solution disposed in a second container; and(c) a third edible solution having a known viscosity equal to or greaterthan about 3000 cp at about 23° C., the third edible solution disposedin a third container.
 2. The kit according to claim 1, wherein thesecond edible solution has a viscosity of between about 300 cp to about500 cp.
 3. The kit according to claim 1, wherein the second ediblesolution has a viscosity of between about 500 cp to about 1500 cp. 4.The kit according to claim 1, wherein the third edible solution has aviscosity of between about 3000 cp to about 5000 cp.
 5. The kitaccording to claim 1, wherein the third edible solution has a viscosityof between about 3000 cp to about 4000 cp.
 6. The kit according to claim1, wherein the second edible solution has a viscosity of between about300 cp to about 500 cp, and the third edible solution has a viscosity ofbetween about 3000 cp to about 5000 cp.
 7. The kit according to claim 1,wherein the second edible solution has a viscosity of between about 500cp to about 1500 cp, and the third edible solution has a viscosity ofbetween about 3000 cp to about 5000 cp.
 8. The kit according to claim 1,wherein the second edible solution has a viscosity of between about 300cp to about 500 cp, and the third edible solution has a viscosity ofbetween about 3000 cp to about 4000 cp.
 9. The kit according to claim 1,wherein the second edible solution has a viscosity of between about 500cp to about 1500 cp, and the third edible solution has a viscosity ofbetween about 3000 cp to about 4000 cp.
 10. The kit according to claim1, wherein the first, second, and third edible solutions comprise animaging agent.
 11. The kit according to claim 10, wherein the imagingagent comprises a radio-opaque imaging agent.
 12. The kit according toclaim 11, wherein the radio-opaque imaging agent comprises abarium-containing compound.
 13. The kit according to claim 11, whereinthe radio-opaque imaging agent comprises barium sulfate.
 14. A methodfor evaluating a human subject for dysphagia, the method comprising: (a)providing at least two edible solutions selected from the groupconsisting of: (i) a first edible solution having a known viscosity offrom about 1 cp to about 60 cp at about 23° C., the first ediblesolution disposed in a first container; (ii) a second edible solutionhaving a known viscosity of from about 300 cp to about 2000 cp at about23° C., the second edible solution disposed in a second container; and(iii) a third edible solution having a known viscosity equal to orgreater than about 3000 cp at about 23° C., the third edible solutiondisposed in a third container; and then (b) (i) evaluating swallowing inthe subject for indications of dysphagia during and after the subjectswallows one of the edible solutions; and (ii) evaluating swallowing inthe subject for indications of dysphagia during and after the subjectswallows another of the edible solutions.
 15. The method according toclaim 14, wherein in step (a) the first, second, and third ediblesolutions comprise a radio-opaque imaging agent that does not leave anartificial coating in the mouth and oropharynx after swallowing iscomplete; and in steps (b)(i) and (b)(ii), swallowing is evaluated byradiography.
 16. The method according to claim 14, wherein the first,second, and third edible solutions comprise a non-pulpy fruit juicewherein viscosity of the fruit juice is modified by adding a thickeningagent thereto.
 17. The method according to claim 16, wherein the fruitjuice is apple juice.
 18. The method according to claim 14, wherein thefirst, second, and third edible solutions comprise an imaging agent. 19.The method according to claim 18, wherein the imaging agent comprises aradio-opaque imaging agent.
 20. The method according to claim 19,wherein the radio-opaque imaging agent comprises a barium-containingcompound.
 21. The method according to claim 19, wherein the radio-opaqueimaging agent comprises barium sulfate.
 22. A kit of compositions ofmatter, the compositions capable of being diluted to yieldviscosity-standardized edible solutions for evaluating human subjectsfor dysphagia, the kit comprising at least two compositions of matterselected from the group consisting of: (a) a first composition capableof yielding upon dilution a first edible solution having a knownviscosity of from about 1 cp to about 60 cp at about 23° C.; (b) asecond composition capable of yielding upon dilution a second ediblesolution having a known viscosity of from about 300 cp to about 2000 cpat about 23° C.; and (c) a third composition capable of yielding upondilution a third edible solution having a known viscosity equal to orgreater than about 3000 cp at about 23° C.
 23. The kit according toclaim 22, wherein the first, second, and third edible solutions comprisean imaging agent.
 24. The kit according to claim 23, wherein the imagingagent comprises a radio-opaque imaging agent.
 25. The kit according toclaim 24, wherein the radio-opaque imaging agent comprises abarium-containing compound.
 26. The kit according to claim 24, whereinthe radio-opaque imaging agent comprises barium sulfate.